Water and fire tube for steam boilers



Feb. 26, 1952 (2. R055! WATER AND FIRE TUBE FOR STEAM BOILERS 2 SHEETSHEET 1 Filed March 14, 1949 ilillflilllllll'ff G. ROSS] WATER AND FIRETUBE FOR STEAM BOILERS Filed March 14, 1949 Feb. 26, 1952 2 SHEETSSHEET2 Patented Feb. 26, 1952 WATER AND FIRE TUBE FOR STEAM BOILERS GiovanniRossi, Valle Lomellina, Italy Application March 14, 1949, Serial No.81,382 In Italy March 13, 1948' 2 Claims. (Cl. 122114) The presentinvention relates to a water and fire tube for a steam boiler or otherheat exchanger.

One of the objects of the present invention is to provide a water andfire tube element of the above type which increases the turbulence offiuids flowing therethrough as the temperatures of these fluids decreaseso as to heighten the heat exchange between these fluids during suchperiods of temperature decrease.

Another object of the present invention is to provide water and firetube elements of the above type which may be easily added to or removedfrom a heat exchanger to vary the capacity thereof.

With the above objects in view, the present invention mainly consists ofa water and fire tube element comprising an outer elongated tubular bodyformed with inlet and outlet openings adjacent opposite ends thereof,respectively. An inner tubular body is located within this outer tubularbody, extends in the longitudinal direction thereof, and has oppositeopen inlet and outlet portions which pass through the wall of the outertubular body, this inner tubular body being at least partially formedwith a plurality of annular corrugations which are spaced from eachother by progressively decreasing distances in the direction from theinlet end portion to the outer end portion of the inner tubular body.Where the corrugations do not extend over the entire length of the innertubular body, it is preferredthat they be located adjacent to the out"let end portion of the inner tubular body.

The outer tubular body may carry water and steam therethrough incounterfiow to hot gases passing through the inner tubular body. The.

above-mentioned corrugations, in addition to enhancing the heat transferbetween the fluids also serve to compensate for deformations resultingfrom thermal expansions and contractions of the inner tubular body. Aseparate helicoidal diaphragm may be located within the inner tubularbody in order to create further turbulence of the gases so as to therebyimprove the heat exchange between the fluids.

Thenovel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself. however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read .in connection with the accompanying drawings, inwhich:

Fig. 1 illustrates an elevational, partially sectional view of onepossible embodiment of a water and fire tube element construction inaccordance with the present invention;

Figs. 2-5 are elevational, sectional views of different embodiments,respectively, of the structure illustrated in Fig. 1;

Fig. 6 is an elevational, fragmentary view of one possible manner inwhich a plurality of water and fire tube elements of the presentinvention may be combined;

- Fig. 7 is a partially sectional, plan view of the structure shown inFig. 6;

Fig. 8 is an elevational, fragmentary view of another possible manner inwhich a plurality of water and fire tube elements of the presentinvention may be combined together;

Fig. 9 is a side view of the structure shown in Fig. 8;

Fig. 10 is a partially sectional, plan view of the structure shown inFig. 8;

Figs. 11-15 are elevational, sectional views of still furtherembodiments, respectively, of water and fire tubes constructed inaccordance with the present invention; and

Fig. 16 is a diagrammatic sectional view of a boiler including tubesconstructed in accordance with the present invention.

Referring now to the drawings, there is shown in Fig. 1 a water and firetube construction which includes the outer tubular body A having theinner tubular body B mounted therein and forming a smoke tube for hotgases, while tube A forms a water tube. The tube A is provided at itsopposite ends, respectively, with the tubes C and D, tube C being theoutlet for the water and steam and the tube D forming an inlet for thewater. The hot gases enter through the top part of tube B, shown in Fig.1, and discharge from the lower part thereof, so that the hot gases andwater flow in countercurrent to each other, as shown by the arrows inthe drawings. The structures illustrated in Figs. 1 and 4 to 10 areprovided with an outlet means H, as shown in the drawings, to permit thecleaning and removal of sediment from the water tube A.

In the construction illustrated in Fig. 1, the upper opening Nof thetube B is located coaxially with the tube..A and the edge portion of theopening N is :fixed to the spherically-shaped end P of the body A bymeans of soldering, for example. The lower end M of the tube B islaterally bent so that it passes laterally through the wall of tube A,and the gases fiow in the direction of thearrow's. Within the tube Bthere is located the helicoidal diaphragm K mounted on a centralsupporting rod. This helicoidal diaphragm K provides a turbulent flow inthe hot gases so as to improve the heat transfer between the fluids.Diaphragm K may be easily removed, for cleaning purposes, by slipping itupwardly and outwardly of the tube B.

In order to prevent excessive stresses in the tube B because ofdeformations due to thermal contraction and expansion, the tube B isformed with peripheral, annular corrugations R which automaticallycompensate for the expansions and contractions to which the tube B issubject. These corrugations are preferably located adjacent the outletend of the tube B so that these corrugations will produce a furtherturbulence in the gas, after it has given up the greater part of itsheat in the upper portion of the tube B, for the purpose of increasingthe heat transfer from these relatively cool gases located adjacent theoutlet end of the tube B.

In the embodiment of the invention which is illustrated in Fig. 2, theopenings N and M are coaxial with each other and with the axis of thetube A. This arrangement in addition to permitting an easier and moreefiicient cleaning of the structure, also permits the tube B to befastened to the tube A by spreading the ends of the tube B outwardly, asshown in Fig. 2.

In the embodiment of Fig. '3, the ends N and M of the tube B are alsocoaxial with each other, but in this embodiment the axis of the tube Bis inclined to that of the tube A in order to improve the circulation ofthe water and steam.

In the embodiment of Fig. 4, the tube A is provided with spherical endsP and P, and both ends N and M of the tube 3 are laterally bent inopposite directions and pass through the wall of the tube A.

In the structure of Fig. 5, the tube A is closed at its ends by theperforated plate members L and L' which are fastened to the ends of thetube A by soldering, for example. The ends N and M of the tube B passthrough the perforated plates L and L and are expanded, as shown in Fig.5, so as to fixedly join the tube B to the plates L and L. The tubes C,D and H are fastened to the wall of tube A of the embodiment of Fig. 5by any suitable means, such as soldering or expanding, and these tubesall pass through the wall of the tube A.

Figs. 6 and '7 illustrate one manner in which a plurality of theabove-described water and fire tube elements may be joined to eachother. In the arrangement of Figs. 6 and 7, the downcomers D for leadingthe water to the bottom of the tube A are located between adjacent tubesA so as to form a wall with the latter. In Figs. 8 to 10 there isillustrated a variation of the arrangement of Figs. 6 and '7, in thatthe single tube D located in the tubes A and A simultaneously suppliesboth of these tubes. Also, the arrangement of Fig. '6 includes separatesediment outlets H, whereas the arrangements of Figs. 8 to 10 include asingle sediment outlet H common to a pair of adjacent tubes A.

In the structure illustrated in Figs. 11 to 15,

. the outer tubular body A has its opposite ends P and P tapered so asto each form a collar '1' which retains an end of the inner tube Bmounted coaxially within the tube A. In Figs. 11 to 13, the ends of thetubes B are cylindrical and the collars T retaining these ends are alsocylindrical. The tubes B are mounted with a tight, press fit in thecollars T, so that the soldering seam V located at the outer ends of theadjoin ing tubular bodies only serves the purpose of eliminatingpossible small losses by providing a more perfect seal, the mechanicalstresses resulting from internal pressures being absorbed by the tubes Aand B. When it is necessary to remove the sediment from the inside oftubular body A, all that is required is the removal of the solder V byfiling, grinding or melting, so that the inner tube B may be easilypushed out to give access to the interior of tube A. After the sedimenthas been removed, tube B may be easily replaced and again soldered inits original position, This latter operation may be repeated as manytimes as desired.

In Fig. 12 the internal tube B is provided with corrugations R whichprogressively increase in depth in the direction from the top to thebottom of the tube B, so that, as the temperature of the hot gasesdecreases, the turbulence thereof is increased so as to increase theheat exchange with the decreased temperature of the gases. Thecorrugations R may be formed of individual annular corrugations or of asingle helicoidal corrugation. If desired, the variation in the amountof turbulence may also be obtained by progressively varying the pitch ofthe corrugations along the tube B, as shown in Figs. 13 and 15 where thedistances between adjacent corrugations gradually decrease toward thelower end of the tube B.

The supply tube D provides a support for the construction shown in Fig.11, for example, when the latter is arranged with its axis extending ina vertical direction, and the tube D has connected thereto the brace Swhich is preferably tubular so as to provide for water circulationthrough the elements S and D for the purpose of preventing deteriorationof the brace 5 when in contact with the hot gases. As is shown in Fig.13, the bottom opening M of the gas tube B is joined to a curved tube Wfor discharged gases, which are thus directed transversely in adirection away from the furnace Wall which may be formed by several ofthe tube constructions shown in Fig. 13, as described above inconnection with Figs. 6 to 10.

In the arrangement illustrated in Fig. 14, the seal between the tubes isobtained by means of a pair of metallic packing rings Z, which may bemade of copper, for example. These rings Z are each pressed between theadjoining ends of the bodies A and B, these ends preferably beingcone-shaped so as to permit the packings Z 1 to be pressed. To preventthe inner tubeB from slipping out in an upward direction, its lowerperipheral end is spread outwardly, as shown in Fig. 14, or it may besoldered to tube A, as shown in Figs. 11 to 13.

In Fig. 15, the packing rings Z are respectively pressed between the endcollars of the tube B and the bell-shaped ends T of the tube A. The

lower ends of tube B may be spread outwardly freeexpans'ion of tubes B.The seal is obtained by means'of a packing ring 0 which is pressedbetween the edge portion U of the lower plate E and the body A, theperipheral edge U' of the tube M, which is the outlet for the gases,also pressing against the packing 0. Tube M is connected to the body Aby means of screw members or other similar devices. The heat exchangershown in Fig. 16 obviously may have the details thereof varied to adaptthe same for particular uses.

The above-described structure permits the construction of a boiler ofdesired capacity simply by varying the number of water and fire tubeelements of the invention, these latter elements being convenientlystored away. The above-described boiler has an extremely large capacity,considering the size thereof, and is easy to maintain, particularly whenthe inner tubes are readily accessible at both ends thereof.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofwater and fire tube elements diifering from the types described above.

While the invention has been illustrated and described as embodied inwater and fire tubes for steam boilers, it is not intended to be limitedto the details shown, since various modifications and structural changesmay be made without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A water and fire tube element comprising, in combination, an outerelongated tubular body formed with inlet and outlet openings adjacentopposite ends thereof, respectively; an inner tubular body locatedwithin said outer tubular body, extending in the longitudinal directionthereof and having opposite open inlet and outlet end portions passingthrough the wall of said outer tubular body, said inner tubular bodybeing at least partially formed with a plurality of annular corrugationswhich are spaced from each other by progressively decreasing distancesin the direction from said inlet end portion to said outlet end portionof said inner tubular body.

2. A water and fire tube element comprising, in

combination, an outer elongated tubular body formed with inlet andoutlet openings adjacent opposite ends thereof, respectively; an innertubular body located within said outer tubular body, extending in -thelongitudinal direction thereof and having opposite open inlet and outletend portions passing through the wall of said outer tubular body, saidinner tubular body being at least partially formed with a plurality ofannular corrugations which are spaced from each other by progressivelydecreasing distances in the direction from said inlet end portion tosaid outlet end portion of said inner tubular body, all of saidcorrugations being located adjacent to said outlet end portion of saidinner tubular body.

GIOVANNI ROSSI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 423,664 Brown H- Mar. 18, 1890780,535 Steber Jan. 24, 1905 1,077,160 Reese Oct. 28, 1913 1,211,858Johnson Jan. 1, 1917 1,349,571 Hubbard "Aug. 17, 1920 1,775,638 GouldSept. 16, 1930 1,859,745 Morely May 24, 1932 2,468,903 Villiger May 3,1949 FOREIGN PATENTS Number Country Date 15 Great Britain Jan. 2, 188821,464 Great Britain Nov. 12, 1895 26,987 Austria Jan. 10, 1907 399,468France June 29, 1909

